Juniper MX240 Hardware Manual page 387

8. Secure each power cable lug to the terminal studs, first with the flat washer, then with the nut (see
Figure 137 on page 393). Apply between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each nut.
Do not overtighten the nut. (Use a 7/16-in. [11 mm] torque-controlled driver or socket wrench.)
a. Secure the positive (+) DC source power cable lug to the RTN (return) terminal.
b. Secure the negative (–) DC source power cable lug to the –48V (input) terminal.
CAUTION:
the terminal block as you are tightening the nuts. Ensure that each nut is properly
threaded onto the terminal stud. The nut should be able to spin freely with your
fingers when it is first placed onto the terminal stud. Applying installation torque
to the nut when improperly threaded may result in damage to the terminal stud.
CAUTION:
supply is 36 lb-in. (4.0 Nm). The terminal studs may be damaged if excessive
torque is applied. Use only a torque-controlled driver or socket wrench to tighten
nuts on the DC power supply terminal studs.
CAUTION:
polarity. The power source cables might be labeled (+) and (–) to indicate their
polarity. There is no standard color coding for DC power cables. The color coding
used by the external DC power source at your site determines the color coding
for the leads on the power cables that attach to the terminal studs on each
power supply.
NOTE: The DC power supply in PEM0 must be powered by dedicated power feeds derived
from feed A, and the DC power supply in PEM2 must be powered by dedicated power
feeds derived from feed B. This configuration provides the commonly deployed A/B feed
redundancy for the system.
NOTE: For information about connecting to DC power sources, see
Electrical Specifications for the MX240 Router" on page
Ensure that each power cable lug seats flush against the surface of
The maximum torque rating of the terminal studs on the DC power
You must ensure that power connections maintain the proper
"DC Power Supply
58.
391